Interface TestInstanceFactory

All Superinterfaces:
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface @API(status=STABLE, since="5.7") public interface TestInstanceFactory extends Extension
TestInstanceFactory defines the API for Extensions that wish to create test instances.

Common use cases include creating test instances with special construction requirements or acquiring the test instance from a dependency injection framework.

Extensions that implement TestInstanceFactory must be registered at the class level.


Only one TestInstanceFactory is allowed to be registered for any given test class. Registering multiple factories for any single test class will result in an exception being thrown for all tests in that class, in any subclass, and in any nested class. Note that any TestInstanceFactory registered in a superclass or enclosing class (i.e., in the case of a @Nested test class) is inherited. It is therefore the user's responsibility to ensure that only a single TestInstanceFactory is registered for any specific test class.

Constructor Requirements

Consult the documentation in Extension for details on constructor requirements.

See Also:
  • Method Details

    • createTestInstance

      Object createTestInstance(TestInstanceFactoryContext factoryContext, ExtensionContext extensionContext) throws TestInstantiationException
      Callback for creating a test instance for the supplied context.

      Note: the ExtensionContext supplied to a TestInstanceFactory will always return an empty Optional value from getTestInstance() since the test instance cannot exist before it has been created by a TestInstanceFactory or the framework itself.

      factoryContext - the context for the test class to be instantiated; never null
      extensionContext - the current extension context; never null
      the test instance; never null
      TestInstantiationException - if an error occurs while creating the test instance